Before summer rears its hot, humid head, there are some winter dishes I’m not ready to bid adieu. While strolling the market a few months ago, I happened upon a pile of onions. Actually, it was more like tripped over them. Anyone who’s spent a winter season in the northeast knows January is the land of root vegetables and tubers.
On this particular trip I was looking for some savory tart inspiration, and the onions set off a light bulb. What if I could capture the flavor of a hearty, French onion soup, complete with the gooey, golden cheese-laced top. I went home, a sack of onions and fresh thyme in hand. A pit stop once I emerged from the train yielded a chunk of gruyere cheese. All of the other ingredients were in the pantry at home.
Well, that tart has gotten me into a bit of trouble now. See, I’m smitten with it, and the thought of saying goodbye is almost too hard to bear. Luckily it’s a nice compromise for the warmer weather on the horizon. Served with a salad, it makes for an oddly light meal. The flavor is intense, yet you don’t feel weighed down the way one would after eating a crock of traditional French onion soup.
And if you’re worried about heating up an already hot house as the temperatures outside rise, then take comfort in knowing it reheats amazingly well. Make this tart at night when the weather is cooler, and you’ll be more than eager to wake the next morning, knowing what’s in store for dinner.
French Onion Tart
Serves 6 to 8
For the filling:
1 to 2 tablespoons extra virgin olive oil
2 pounds yellow onions, peeled & sliced thin
Sea salt and freshly ground pepper, to taste
1 large egg, lightly beaten
2 sprigs of fresh thyme, leaves removed & stems discarded
1 teaspoon sherry vinegar
2 ounces Swiss cheese, shredded
For the Swiss cheese crust:
3/4 cup (110 grams) whole wheat pastry flour
1/4 teaspoon (2 grams) fine sea salt
1/4 teaspoon hot paprika
1 cup (3 ounces) Swiss cheese, shredded
4 tablespoons (2 ounces) very cold butter, shredded using a box grater
1 to 2 tablespoons cold seltzer
- To make the filling, heat the olive oil in a heavy-bottomed pot over medium-high heat. Add the onions and saute for 2 minutes. Cover pot, reduce heat as low as it can go without shutting off, and let cook until onions have cooked down and released a lot of their liquid, about 20 minutes.
- Meanwhile, prepare the crust. Add the flour, salt, and paprika to the bowl of a food processor. Pulse once or twice to mix the dry ingredients. Add the cheese and butter, then pulse a few times until it forms a sandy-looking mixture. Add 1 tablespoon of seltzer, pulse again until a rough ball of dough comes together. If the mixture is too dry and crumbly, add more seltzer 1 teaspoon at a time (you may not need the entire 2 tablespoons), and continue to pulse until you have a ball of dough. Turn the dough out onto an unfloured counter, flatten and shape into a disk. Wrap in plastic wrap and chill for 30 minutes.
- Preheat the oven to 400ºF.
- Remove cover from the pot of onions, raise heat to medium, add the thyme and season with salt and pepper. Let the onions cook, stirring occasionally to scrape the browned bits from the bottom of the pot, until onions turn golden brown, about 30 to 35 minutes. When onions are golden and very tender, stir in the sherry vinegar. Remove from heat and, using a slotted spoon, transfer onions to a medium bowl.
- Place the chilled dough between two sheets of parchment paper, and roll it into a 13-inch circle. Fit dough into a 9-inch ungreased springform pan. Fold down sides of dough, leaving a 1-inch high crust.
- Add the egg and cheese to the bowl with the onions. Stir to mix well. Pour the filling into the pan and spread to the edges using a rubber spatula. Bake for 25 minutes, until slightly puffed and golden. Remove from oven and let cool for 5 to 10 minutes before slicing.